gp_enable_adaptive_nestloop

gp_enable_adaptive_nestloop

Enables the use a new type of join node called "Adaptive Nestloop" at query execution
time by the legacy query optimizer (planner). This causes the legacy optimizer to favor a
hash-join over a nested-loop join if the number of rows on the outer side of the join
exceeds a precalculated threshold. This parameter improves performance of index
operations, which previously favored slower nested-loop joins.